Thin metal sheet tapered receptacles and method and apparatus for producing the same



3,182,482 THIN METAL SHEET TAPERED RECEPTACLES AND METHOD p w L L 5 o 1 m L a M R d 8 J n F May 11, 1965 AND APPARATUS FOR PRODUCING THE SAME a a Z 6 r y 4 U Z J v a ll! 5 II WW mu 9 lllw z wfl a, 1/ mmw Iva/ 1 f r 6 W L A I III 4 a ,J z z w m F FIG.2

BY vi HIS ATTORNEY United States Patent Delaware Filed Mar. 15, 1961, Ser. No. 95,957 Claims. (Cl. 72350) This invention relates to the manufacture of receptacles from relatively thin metal sheets, and is particularly directed to the press drawing of tapered side wall receptacles without the formation of wrinkles. In its more specific aspect it concerns the manufacture of such receptacles from aluminum or aluminum alloys in thin or foil-like sheets.

For the sake of brevity, whenever the word aluminum is used in this application in a broad sense, it is intended to refer to aluminum and its alloys which are proper for this type of manufacture.

When a thin sheet of aluminum or similar metal is drawn into the form of a relatively deep, tapered receptacle, the side wall structure of the receptacle is wrinkled, and particularly so along any curved portions of the side wall structure. One of the reasons for this wrinkling action is that the side wall forming portion of the thin sheet is pulled tension between the relatively large leading mouth of the die member and the relatively small leading face of the punch member. This pull between the relatively large perimeter of the die mouth and the relatively small perimeter of the punch leading face inherently produces wrinkles because the larger area of the sheet which surrounds the mouth of the die contracts over the die mouth into the narrower side wall of the receptacle, and becomes wrinkled during such contracting process.

For example, when a relatively thin sheet of aluminum of 0.010 inch thickness is drawn into a substantially square, deep receptacle with rounded corners, and with tapered sides, the side walls are wrinkled, particularly along the rounded corners. As a further detailed example, such a substantially square receptacle has been made, which is 5.830 inches between the top straight inside rim edges, 5.330 inches between the straight bottom edges. The corners are circularly rounded with a radius of 1.000 inch along the rim top, and the deph of the receptacle is 2.25 inches from the top of the rim to the lowest part of the bottom edge. A very pronounced wrinkling effect has been produced, particularly along the rounded corners, as the flat sheet is pulled down (or up as the case may be) over the rounded mouth corners of the die.

The above indications of size, thickness of sheet, shape and taper of receptacle are given to indicate only in a general way the nature and scope of the invention.

According to this invention, means are provided to prevent the formation of such wrinkles in this general type of receptacle, and it is among the objects of this invention to provide methods, apparatus, and products in which such wrinkling of the side wall of the receptacle is prevented.

Other objects and advantages will become apparent as the description proceeds with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic representation of the die press with the punch and die separated.

FIGURE 2 is a similar view with the punch and die brought together.

FIGURE 3 is a cross section of the receptacle produced by the press of FIGURES 1 and 2.

3,l82,42 Patented h'llay ll, I965 FIGURE 4 is a perspective view of the receptacle shown in FIGURE 3.

FIGURE 5 is an enlarged cross-section of a portion of FIGURE 2.

FIGURE 6 is an enlarged cross-section showing the ring in unflexed condition.

A drawing die press, according to this invention, may include a die member 20, and a punch member 22. Means are provided for moving these members relatively toward and away from each other, such as plunger rods 24, which move the die member downwardly when the punch member is below the die member. As is well known, the members 20 and 2.2 may be inverted, with the punch above and the die below.

The punch member 22 is surrounded by a press plate 26 which is resiliently supported by the rods 28 which pass through the base late 30 and which engage spring constructions, well known, which move the press plate 26 up to the position shown in FIGURE 1, and allow the press plate 26 to be moved down by the flat surface 32 of the combined press plate and leading die edge plate 34 of the die 20.

The punch 36 is slightly tapered and is secured to an untapered portion or plate 38, which supports the tapered punch 36 on the base plate 30.

A knock out pad or plate 40 is placed in the upper cavity of the die 20, and is actuated by the plunger 42 at the proper time to knock out the receptacle after it has been formed in the press.

The members so far described in connection with the press are shown in dotted lines, since they may be of any well known construction suitable for the purpose herein set forth.

The press may be of any desired size and may produce receptacles of any desired shape, in accordance with the disclosure of this application. For example, the press of this type may produce substantially square, slightly tapered, receptacles of the shape and size herein shown and described in connection with FIGURES 3 to 6.

According to this invention, the press so far described may be provided with means cooperating with the slight taper of the punch and die members to prevent formation of wrinkles in the sheet being drawn, as it passes over the curved, relatively large leading perimeter 48 of the die mouth, in cooperation with the relatively small curved perimeter 50 of the punch leading face 52.

The means for preventing formation of wrinkles may take the form of a flexible ring 54, made of nylon or Teflon, which is embedded in one of the die or punch members, and which is illustrated as being located in the die member. This ring 54 provides a flexible work stroking surface, which strokes the work or thin sheet blank 56 just after it has been pulled inwardly around the curved perimeter 48 of the die mouth.

Preferably the ring 54 is U-shaped, with the open end 58 directed in the press closing directions, and with the inner leg 60 being resiliently bendable inward during the drawing operation, as is shown in FIGURES 2 and 5. The ring 54 is embedded in a groove 61 formed in the wall 62 of the die member, which wall would have been gently tapered, as indicated at 63, FIGURE 6, to match the tapered wall 64 of the punch 36, except for the addition of the resilient ring 54. The leg 60 bulges inward toward the center of the die at its open end 58, as shown in FIGURES 1 and 6, extending slightly inward at 45, FIGURE 6, from the tapered surface 46 of the die memher, so as to produce the stroking action which eliminates the wrinkles which otherwise would have been produced in the receptacle. One or more radial bores 67 extend to the outer surface of the press and permit air to enter into and discharge from the interior of the ring 54.

In the case of a substantially square receptacle, with rounded corners, as previously described, the flexible ring 54 is particularly effective where it is embedded around the corners of the working faces of the die or punch and where the wrinkling action is particularly pronounced as in the case of such a square receptacle.

The wall of the ring 54 was approximately A; inch wide at the top 68, 1 and inches high along the side 69, inch thick at each leg 66 and 60a, and inch thick at 690, FIGURE 6, for the size of receptacle of FTGURES 3 and 4. The unfle'xed legs 60 and 66a were 1 and inches apart at 58a.

When square receptacles of the character and size hereinbefore described were drawn in a press of the character shown in FIGURES 1 and 2, but without the ring 54, and with the previous solid tapered inner surface of the die, the receptacles had a very pronounced wrinkled con struction at the corners. However, when such a press was provided with the flexiblering 54, to embody this in: vention, then the receptacles drawn by such a press were wrinkle free throughout the entire side wall construction, as well as throughout the. remainder of the wall construction of the receptacle. This wrinkle free result was, it is believed, due to the stroking action of the flexible ring 54, which acted upon the receptacle wall immediately after it had been drawn around curved edge 48 of the die mouth.

Receptacles formed by the die drawing press shown in FIGURES 1 and 2 were substantially of the character shown in FIGURES 3 and 4 in which the sheet of aluminum was of 0.010 inch in thickness and was drawn into a substantially square deep receptacle with rounded corners 76 and with tapered side walls '72. The receptacles were 5.830 inches between the straight inside rim edges of the receptacle and were 5.330 inches between the straight bottom edges as indicated by the lines a and b respectively in FIGURES 3 and 4. The corners were circularly rounded with a radius 1.000 inch, as indicated by radius line inFIGURE 4. The depth of the receptacles was 2.25 inches from the top of the rim to the lowest part of the bottom edge as indicated by line :1 in FIGURE 3. It is understood that, in general use, the receptacle shown in FIGURES 3 and 4 is inverted, so that the rim is at the top instead of at the bottom as shown in the FIGURES 3 and 4.

Receptacles of slightly diiierent shape, with or without covers, can also be drawn with wrinkle free side walls (except where purposely indented).

The invention is not limited to the sizes and shapes of the receptacles or to the thickness of the sheet being used, and such sizes, shapes and thicknesses can be varied pro portionally with the teachings of the examples given, as will now be apparent to those skilled in the art. Receptacles of many rectangular shapes, as well as oblong, circular and irregular shapes, sizes and wall thicknesses can be used. Depths of receptacle as much as 50% of the horizontalarea or the like can be used. The taper can be varied within the teachings of this invention. Many different types of surface lubricants may be used.

While the form of the invention has been shown, as required by the statutes, many other forms can be used, all coming within the scope of the claims which follow.

What is claimed is:

1. A drawing die press comprising: a female die member having a surface surrounding the cavity thereof; a punch member; a press plate cooperable with said surface of said die member to hold a sheet of material thereagainst with said sheet of material spanning said cavity;

means for moving said members relatively toward and away from each other to cause said members to draw said sheet of material into said cavity and form a cup-shaped receptacle with the outer peripheral portion of said sheet still being held between said press plate and said surface of said die member; and a wrinklereducing flexible ring secured on one of said members adjacent the working face of said last named member to provide a flexible work stroking surface for stroking the side wall means of said receptacle while said receptacle is being drawn between said members.

2. A press according to claim 1, in which the wall of said ring is U-shaped in cross-section.

3. A press according to claim 1, in which the wall of said ring is U-shaped in cross-section with the open end of the U directed in the press closing direction.

4. A drawing die press comprising: a female die memher having a surface surrounding the cavity thereof; a punch member; a press plate cooperable with said surface of said die member to hold a sheet of material thereagainst with said sheet of material spanning said cavity; means for moving said members relatively toward and away from each other to cause said members to draw said sheet of material into said cavity and form a cup-shaped receptacle with the outer peripheral portion of said sheet stillbeing held'between said press plate and said surface of said die member; and a flexible wrinkle reducing means embedded in the working face of one of said members to provide a flexible work stroking surface for stroking the side wall means of said receptacle while said receptacle is being drawn between said members.

5. A drawing die press comprising: a female die memher having a surface surrounding the cavity there; a punch member receivable in said cavity; a press plate cooperable with said surface of said die member to hold a sheet of material thereagainst with said sheet of material spanning said'cavity; means for moving said members relatively toward and awayfrom each other to cause said members to draw said sheet of material into said cavity and form a cup-shaped receptacle with the outer peripheral portion of said sheet still being held between said press plate and said surface of said die member; and means for preventing the production of wrinkles during the drawing operation of a slightly tapered side wall receptacle, said last-named means comprising a flexible work stroking surface on one of said members for stroking the side wall means of said receptacle when said receptacle is being'drawn between said members.

References Cited by theExaminer V UNITED STATES PATENTS 1,272,751 7/18 Winter 113-46 2,064,518 12/36 Brogden 220-97 2,342,858 2/44 Hansen 113-46 XR 2,599,727 6/52 Schmidt 220-97 2,783,728 3/57 Hoifmann 113-46 XR 2,888,894 6/59 Byerlein 113-46 2,947,273 8/60 Dehn 113-46 2,988,032 6/61 Voissem 113-51 2,989,019 6/61 VanSciver 113-51 FOREIGN PATENTS 621,629 4/49 Great Britain. 674,766 7/52 Great Britain.

WILLIAM J. STEPHENSON, Primary Examiner.

FRANK T. GARRETT, Examiner. 

1. A DRAWING DIE PRESS COMPRISING: A FEMALE DIE MEMBER HAVING A SURFACE SURROUNDNG THE CAVITY THEREOF; A PUNCH MEMBER; A PRESS PLATE COOPERABLE WITH SAID SURFACE OF SAID DIE MEMBER TO HOLD A SHEET OF MATERIAL THEREAGAINST WITH SAID SHEET OF MATERIAL SPANNING SAID CAVITY; MEANS FOR MOVING SAID MEMBERS RELATIVELY TOWARD AND AWAY FROM EACH OTHER TO CAUSE SAID MEMBERS TO DRAW SAID SHEET OF MATERIAL INTO SAID CAVITY AND FORM A CUP-SHAPED RECEPTACLE WITH THE OUTER PERIPHERAL PORTION OF SAID SHEET STILL BEING HELD BETWEEN SAID PRESS PLATE AND SAID SURFACE OF SAID DIE MEMBER; AND A WRINKLE REDUCING FLEXIBLE RING SECURED ON ONE OF SAID MEMBERS ADJACENT THE WORKING FACE OF SAID LAST NAMED MEMBER TO PROVIDE A FLEXIBLE WORK STROKING SURFACE FOR STROKING THE SIDE WALL MEANS OF SAID RECEPTACLE WHILE SAID RECEPTACLE IS BEING DRAWN BETWEEN SAID MEMBERS. 